In LTE (Long Term Evolution) advanced, wider bandwidth is achieved by aggregating component carriers either contiguously or non-contiguously. The component carriers are backward compatible with the ones defined in LTE Rel-8. For contiguous carrier aggregation, consecutive spectrum is aggregated. On the other hand, discontiguous bands are accumulated for non-contiguous carrier aggregation.
Finding the positions of user terminals in a communication system has been in focus for some time, one example includes the use of the GPS (Global Positioning System) in the user terminal. Another way is to use DOA (Direction Of Arrival) estimations at the base stations. With help of the DOA estimations, the direction of the user terminal with respect of the base station could be found. The knowledge of the direction of the user terminal could then be combined with the knowledge of the time delay between the base station ant the user terminal to find the position of the user terminal. By combining DOA estimations from several base stations, the user terminal positions can also be found by means of triangulation. The DOA estimation is typically done in base stations by using sounding signals transmitted from the user terminals.
However, existing solutions can still be improved such that the DOA can be estimated with higher accuracy.
There is thus a need for estimation of DOA with higher accuracy then is provided by means of existing solutions.